This invention relates to chassis for holding telecommunications cards such as repeater circuits. More specifically, the present invention relates to chassis and cards with structures for flame spread containment and/or high card density.
It is desirable for a chassis for holding telecommunication circuit cards to support a high density of cards, yet the chassis must effectively dissipate heat developed during operation while containing the spread of flames should a fire be imposed within the chassis. The cards installed in the chassis perform electrical operations, such as signal transception and amplification that generate a significant amount of heat. Typically, a chassis is installed in a rack that contains several other chassis stacked above and below. The heat and flames that may develop within a chassis in the rack have the potential to harm circuit cards housed in the chassis above and below the chassis where the heat and/or flames emanate from, and the flames should be contained to avoid damaging cards in the other chassis.
The chassis must also provide external protection for the circuit cards it houses. Thus, the chassis cannot freely expose the circuit cards to areas outside the chassis when attempting to dissipate heat and flames. Additionally, the chassis must provide a structural interconnection that maintains electrical continuity between the circuit cards and external transmission mediums such as copper wires or fiber optic cables while facilitating insertion and removal of the cards. A sufficient structure must be used to facilitate this circuit card modularity, which further limits the chassis"" ability to provide outlets for heat and flames.
Additionally, to reduce the chassis size for a given number of circuits, the circuit card density must be increased. Increasing circuit card density is difficult not only due to heat dissipation and potential flame spread, but also because of electromagnetic noise that must be contained. Generally, increasing circuit card density involves employing smaller cards, and smaller cards require higher component density within the cards. Achieving effective heat dissipation with adequate flame spread and electromagnetic noise containment may even be more difficult for smaller card designs with higher component densities.
Thus several factors must be accounted for in the chassis and card design. Chassis designs with large interior spaces for directing heat and flames away from circuit cards may be undesirable because the chassis may become too large when accommodating a high density of circuits. Chassis designs with open exteriors for directing heat and flames away from the circuit cards may be undesirable because the circuit cards may not be sufficiently protected from externalities such as falling objects or heat and flames spreading from a chassis positioned above or below in the rack. Card designs that are relatively large require a larger chassis to house the same quantity of cards.
Thus, there is a need for a chassis and card design whereby the chassis may contain a high density of readily removable circuit cards while providing effective heat dissipation and flame and electromagnetic noise containment.
The present invention provides a chassis and card design that may accommodate a high density of readily removable circuits while providing heat dissipation and flame and electromagnetic noise containment features. Ventilation and containment structures are employed to direct heat away from internal circuitry while preventing flames from spreading within the chassis. Additionally, chassis designs of the present invention may provide exterior features that establish protection from externalities and prevent the harmful spread of heat and flames to chassis or other equipment stacked above or below. Card designs of the present invention may provide conductor structures for containing electromagnetic noise and/or individual components placed in locations for coordination with the ventilation structures of the chassis.
The present invention may be viewed as a chassis for housing repeater cards. The chassis includes an inner housing with vertical sidewalls, a first surface, and a second surface. The first surface and the second surface have a first and second row of openings. The chassis also includes one or more repeater cards positioned between the first surface and the second surface. The one or more repeater cards has a DCxe2x80x94DC converter and a transceiver with the DCxe2x80x94DC converter being positioned between a first opening of the first row of the first surface and a first opening of the second row of the second surface at least partially aligned with the first opening of the first row of the first surface. The transceiver is positioned between a first opening of the second row of the first surface and a first opening of the second row of the second surface at least partially aligned with the first opening of the second row of the first surface.
The present invention may also be viewed as a repeater card. The repeater card includes a printed circuit board having a ground layer and a power layer separated by a dielectric with the ground layer having a chassis ground plane, a logic ground plane, and a first channel ground plane, and with the power layer having a logic power plane and a first channel power plane. The logic ground plane substantially overlaps with the logic power plane and the first channel ground plane substantially overlaps with the first channel power plane. A DCxe2x80x94DC converter is mounted to the printed circuit board and electrically linked to the logic ground plane, the logic power plane, the first channel ground plane, the first channel power plane, and the chassis ground plane. A transceiver is mounted to the printed circuit board and electrically linked to the DCxe2x80x94DC converter, the logic ground plane, the logic power plane, the first channel ground plane, and the first channel power plane.